1. Field of the Invention
This invention relates to the manufacture of recording tape and, more particularly, to apparatus for applying a coating of a lubricating fluid, such as oil, onto a metallic magnetic recording tape.
2. Description of the Prior Art
In the successful operation of a recording instrument, such as a flight recorder used on aircraft to monitor certain critical operating parameters of the operation of the aircraft, it has been found that metallic magnetic recording tape must have a very low coefficient of friction with the magnetic recording heads. The only known way to reduce the coefficient of friction is by having an extremely thin film of lubricant, typically less than ten micro inches, on the recording surfaces of the tape. The signal transduction efficiency varies as the inverse of the "tape-to-head" spacing.
In the past, a film of lubricant was put on metallic tape by mixing the lubricant in a volatile solution, and the mixture was applied to the tape. The solution evaporated leaving the lubricant on the tape. This method was unsuccessful due to the uncontrollability of the volatile solution which resulted in poor control of the film thickness. Another method which has been utilized for applying a coating or film of lubricant to a surface, such as a tape, involves a wick-fed bar in a position such that the tape would be drawn over the bar picking up lubricant from the bar. This method was also not acceptable due to the poor control of the film thickness.